An estimated 60,000 homosexual men and women serving in the US military look to benefit as US politicians vote to repeal a Clinton-era "don't ask, don't tell" law.

US politicians in the House of Representatives voted 234-194 in favour of the amendment, delivering a huge victory to president Barack Obama, who made the law's removal a major election promise.

But opponents of the change accuse Mr Obama of destabilising the military for the sake of a liberal social agenda.

Chris Neff from the University of California's Palm Centre, a think-tank which monitors the impact of "don't ask, don't tell", says the vote is a massive step forward for both homosexual rights and the US military.

"It makes a huge difference. Not needing to lie every day as a condition of service and adding that additional pressure to you if you're being deployed to Iraq or Afghanistan and being able to write a note to you loved ones," he said.

"Under the previous policy, if you wrote a note to a loved one from Afghanistan, that could be a cause for discharge. Now, you'll be protected and you'll have support mechanisms from the military."

But the battle to remove the law is not yet completely over.

The amendment has yet to pass the Senate and there is still significant opposition to the repeal among the military's senior commanders.

Republicans accuse Mr Obama of using the law to ram through a liberal social agenda at the expense of the military.

They want Congress to wait until a Pentagon study into the effects of repealing the law to military operations is completed.

Republican Howard McKeon says there is no reason not to wait for the results of the Pentagon study, due in December.

"I don't know why we're so afraid to stick with the policy; to listen to the members of the armed services, to give them the opportunity that they have," he said.

"I have letters from each of the chairman and the members of the joint chiefs saying 'we owe that to them; we should not break faith with them'."

However, Mr Neff says most active servicemen and women have no problem serving with homosexuals.

"Seventy five per cent of US service members when they were surveyed, said they already knew or suspected someone who was gay in their unit and it wasn't a problem for them," he said.

"So we already know that gays are serving and they're serving openly in units; the difference is that now, they don't have to worry about losing job for it."

He says there is deep-seated resistance from many to keeping gay people out of the military.

"People who have been in favour of 'don't ask, don't tell' supported it on the basis that homosexuality was incompatible with military service, that it was going to hurt unit cohesion or military readiness and that was in spite of the fact that every government report, even the ones commissioned by the defence department, was never able to support that conclusion," he said.